This invention relates generally to an apparatus for mowing standing crop material and, more particularly, to a mower mounted to the three-point hitch of a tractor and carrying a modular disc cutterbar that severs standing crop material by impact action.
Disc cutterbars have been utilized in agricultural harvesting implements for many years. Each disc cutterbar includes a plurality of transversely spaced disc cutters driven for rotation about a generally vertical axis. Each disc cutter has two or three knives pivotally mounted on the periphery thereof to sever standing crop from the ground through an impact action. For background information on the structure and operation of disc cutterbars, reference is made to U.S. Pat. No. 4,815,262, issued to E. E. Koch and F. F. Voler, the descriptive portions thereof being incorporated herein by reference.
The construction of disc cutterbars has evolved over the years to the configuration of having a modular construction with cutter modules and spacer modules, such as shown in U.S. Pat. No. 4,840,019, issued to L. J. Pingry, the descriptive portions of which are incorporated herein by reference. In some instances, the cutter modules and the spacer modules were integrally formed into one unit such as shown and described in U.S. Pat. No. 4,947,629, issued to R. Ermacora and H. Neuerburg.
A disc mower is typically mounted to the three-point hitch of the tractor providing the source of operative power thereto. The driven components of the disc cutterbar are operatively connected through a conventional drive mechanism to the power-takeoff shaft of the tractor or, possibly to a hydraulic drive mechanism powered from the tractor. The disc mower is provided with a base frame that may be supported from the tractor three-point hitch. The disc cutterbar is pivotally supported from the base frame to be movable between a raised transport position, in which the cutterbar may be generally vertically oriented, and a lowered operative position in which the cutterbar is riding on the ground to sever standing crop material through operation of the rotating disc members and affixed cutting knives.
When the disc cutterbar is lowered to the operative position, there is a need to provide a mechanism at the distal end of the cutterbar to keep objects away from the rotating end disc member.
The drive mechanism between the tractor power-takeoff shaft and the driven components of the disc cutterbar typically include a friction drive apparatus, such as a multi-stranded V-belt entrained around a drive sheave and a driven sheave without the benefit of a spring-loaded idler sheave to keep proper tension in the V-belt. Ensuring that the V-belt is operating at the correct tension is difficult to determine. One known method of determining the proper tension is to measure the deflection of each V-belt at the mid-span with a given perpendicular force. Typically, the operator will merely feel the V-belt as the tension stud nut is torqued to increase the tension in the V-belt. Accordingly, an improved method and apparatus for properly tensioning the V-belt needs to be provided. Preferably, the tensioning of the V-belt would not require the removal of the shielding member or the addition of holes in the shielding member to measure the V-belt deflection.
V-belt tension will decrease from an initial setting due to stretching of the belt and from wearing of the belt over time. The result is that the initial tension setting of a V-belt will lessen over time, which unless corrected will result in belt slippage and excessive wear. On the other hand an over-tensioning the V-belt will result in premature failure of the V-belt, as well as overload of other drive components, such as drive shafts and bearings.
The flotation of the disc cutterbar on the surface of the ground when in the operative position is provided by a flotation spring mechanism interconnecting the base frame of the mower and the support frame for the disc cutterbar. In a preferred embodiment of the disc mower, the flotation spring mechanism needs to be disengaged before the disc mower is removed from its mounting on the tractor. The failure to disengage the flotation spring mechanism to eliminate the spring force exerted thereby will result in a rotation of the disc mower base frame laterally when the lower lift arms of the tractor are disconnected from the three-point hitch pins of the mower.